Eric must be busy with LR5.01 fixes!
I ended up answering my own question.
I shot a test image, and shot a reference image for FF plug-in on my DP2 Merrill camera.
I used Sigma SPP 5.5 to get the RAWs into 16 bit tiff files.
I imported tiffs into LR, and then immediately exported as DNG.
I then took those DNGs into the FF plug-in and it worked fine (apparently - no hiccups, and the final image showed obvious differences).
For those of you wondering why I'd go to all this trouble, it is because the Foveon sensor is sometimes (not all the time - don't ask me to explain because I have zero idea) prone to putting either a magenta cast in skies, or a blue-green cast, OR it sometimes looks almost as though there is a very light magenta blob in the photo. Happens rarely, but when it does it is very difficult to correct in LR or CS6, as it is not "uniform."
Preliminary tests show that using the FF plug-in does a dandy job of fixing it! More testing will confirm. My intention is to shoot reference shots on every outing for a while at my various landscape working apertures. When I see the "magenta effect" appear on any of those shoots, I'm going to tag the reference image for that use. Hopefully, I can come up with 3 or 4 reference image files to use when I occasionally get the "magentas" in a Merrill file.
Thought this might be of interest to some of the DP Merrill-istas here on LuLa.